In Brussels, Belgium, where a major terror attack killed at least 34 people and injured 230 or more on Tuesday, a memorial to those same victims was stormed by right-wing demonstrators on Sunday.

BBC reports a crowd had gathered to cover the Place de la Bourse to pay tribute to those lost and hurt on Tuesday, despite a formally scheduled event's cancellation due to risk of terrorism. Visitors covered the courtyard in an arrangement of flowers. Soon thereafter, the demonstrators arrived, prompting a clash with those present and then heavily equipped riot police.

There was a "really positive atmosphere" before "a bunch of skinheads just turned up, marched into the square, and started a major confrontation with the peace protesters," witness Adam Liston told BBC. "They got in the face of the protesters and police. They set off flares and chanted and it was getting quite ugly."

Soon after congregating, however, the memorial was invaded by 400 or so right-wing hooligans, some of whom waved signs expressing anger against ISIS and terrorism, NBC News reports. Dressed mostly in black, and some wearing hoods or face masks, the group proceeded to trample the memorial, hold out their right arms in Nazi-style salute and shout far-right slogans at the crowd.

Riot police and other security forces at the scene ejected the protesters, at one point using a water cannon on the crowd. According to NBC, 12 demonstrators were arrested after members of the group threw explosive devices at officers.

According to U.S. News & World Report, the bombings — coming just months after a massive terror attack on Paris have effectively "emboldened" European right-wing parties, who have used the opportunity to highlight what they call Western weakness in the face of Islamic fundamentalism.